1. Field of the Invention
The present invention relates to a method of fabricating a liquid crystal display device, and particularly to a method of fabricating a liquid crystal display device capable of improving the efficiency of a glass substrate and reducing the fabrication cost by fabricating liquid crystal display devices having various sizes various driving modes on a glass substrate.
2. Description of the Related Art
In general, a liquid crystal display device is a display device in which data signals including picture information are individually supplied to liquid crystal cells arranged in a matrix form, and the optical transmittance of the liquid crystal cells is controlled to display an image.
FIG. 1 is a plan view showing the structure of a liquid crystal display device according to the related art.
In FIG. 1, the liquid crystal display device 10 includes an attached driving element array substrate 1 and color filter substrate 2. The liquid crystal display device also includes an image displaying unit 13 where a plurality of pixels are arranged in a matrix form and a gate pad unit 14 and a data pad unit 15 respectively connected to gate lines and data lines of the image displaying unit 13. The driving element array substrate 1 has a region along a long side and region along a short side that protrudes beyond the color filter substrate 2. The gate pad unit 14 is formed in the region along the short side region protruding from the driving element array substrate 1 and the data pad unit 15 is formed in the region along the long side region protruding from the driving element array substrate 1.
A scanning signal is applied to the gate lines of the image displaying unit 13 by a gate driving unit through the gate pad unit 14, and an image signal is applied to the data line of the image displaying unit 13 by a data driving unit through the data pad unit 15.
The image displaying unit 13 of the liquid crystal display device 10 includes a plurality of pixels defined by a plurality of data lines to which the image signal is applied and a plurality of gate lines to which the scan signal is applied. Each pixel has a pixel electrode and a thin film transistor on the driving element array substrate I that applies the image signal to the pixel electrode.
The image displaying unit 13 of the color filter substrate 2 has a color filter for displaying color images and a common electrode facing the pixel electrode over the driving element array substrate 1.
The driving element array substrate 1 and the color filter substrate 2 face each other and are attached by a sealant (not shown) printed along an outer edge of the image displaying unit 13. A liquid crystal layer is placed between the attached driving element array substrate 1, and the color filter substrate 2 and a spacer is placed therebetween to maintain a uniform cell gap.
In order to fabricate this liquid crystal display device, a plurality of driving element array substrates is formed on a large substrate made of glass or the like, and a plurality of color filter substrates is formed on a separate large substrate. Thereafter, the two large substrates are assembled (i.e., attached) to each other to form a plurality of liquid crystal display panel regions and are cut into individual liquid crystal display panels.
The process of fabricating the liquid crystal display device may be divided into a driving element array substrate process for forming the driving elements on the driving element array substrate 1, a color filter substrate process for forming the color filter on the color filter substrate 2, and a cell process. These processes of forming a liquid crystal display device will now be described using the accompanying FIG. 2.
In the driving element array substrate process, first, a plurality of gate lines and a plurality of data lines defining a plurality of pixel areas are formed on a driving element array substrate 1 and thin film transistors, or driving elements, are formed and connected to the gate lines and the data lines at each pixel area (S101). Further, the pixel electrode connected to the thin film transistor is formed on the driving element array substrate to drive the liquid crystal layer with the signal applied trough the thin film transistor.
Next, the color filter layer with R, G and B (red, green and blue) colors and the common electrode are formed on the color filter substrate 2 using the color filter process (S104).
Thereafter, alignment layers are deposited over the driving element array substrate and the color filter substrate, and then the alignment layers are rubbed in order to provide an alignment controlling force and/or a surface anchoring force (i.e., so as to set a pre-tilt angle and orientation direction) to the liquid crystal molecules in the liquid crystal layer (S102, S105).
Subsequently, a plurality of spacers is dispersed onto the driving element array substrate 1 to maintain a uniform cell gap between the driving element array substrate 1 and the color filter substrate 2. The sealing material is deposited along the outer edge portion of the color filter substrate 2 and the substrates are compressed to attach the substrates (S103, S106, S107).
The driving element array substrate 1 and the color filter substrate 2 are large glass substrates. In other words, because a plurality of panel regions including the thin film transistor and the color filter are formed on the large glass substrates, the glass substrate is cut to fabricate the individual liquid crystal display panel. (S108). Thereafter, the liquid crystal material is injected into the individual liquid crystal display panels through a liquid crystal injection opening, and then the liquid crystal injection opening is encapsulated to form the liquid crystal layer. Finally, the injected liquid crystal display panel is tested (S109, S110).
Generally, the glass substrate may include a plurality of liquid crystal display panels, for example, 4, 6, 8 or 16 liquid crystal display panels. The technology used to form the plurality of liquid crystal display panels on the glass substrate is a primary factor that determines fabrication efficiency of the liquid crystal display device. Accordingly, techniques for more efficiently using the glass substrate have been studied. Today as large liquid crystal display devices are in greater demand, the fabrication technology affects the competitiveness of liquid crystal display device manufacturers.
In general, as shown in FIG. 3A, liquid crystal display panels 10 having the same size are formed on the glass substrate 20. The glass substrate 20 should have an area large enough to form a plurality of the liquid crystal display panels 10 thereon at set intervals. The glass substrate 20 with the plurality of the liquid crystal display panels 10 is separated to form a plurality of individual liquid crystal display panels 10 leaving behind a region of the glass substrate 20 between the liquid crystal display panels 10 which is discarded after separation. Therefore, the glass substrate 20 may be formed to minimize the interval between liquid crystal display panels 10.
The size of the glass substrate 20 is standardized and depends on the size of the liquid crystal display panel 10 being fabricated. Namely, the standard size of the glass substrate 20 is set so that the glass substrate 20 has an area to most efficiently fabricate the liquid crystal display panels 10. As shown in FIG. 3B, when liquid crystal display panels with a different size need to be fabricated on the standard sized glass substrate 20, a large region of the glass substrate 20 remains unused. This problem may be solved by forming the liquid crystal display panel 10 on a glass substrate 20 with a standard size corresponding to the liquid crystal display panel 10 to be made. But, there may be no glass substrate that is standardized according to the liquid crystal display panel to be made, so the liquid crystal display panel 10 must be formed on a glass substrate 20 with a different standard as shown in FIG. 3B. Accordingly, a large portion of the glass substrate remains unused, and thus the unused region of the glass substrate is discarded, thus increasing the fabrication cost of the liquid crystal display device.